Neurological stimulators have been developed to treat pain, movement disorders, functional disorders, spasticity, cancer, cardiac disorders, and several other medical conditions. Implantable neurological stimulation systems generally have an implantable pulse generator and one or more electrode leads that deliver electrical pulses to neurological tissue or muscle tissue. For example, several neurological stimulation systems for spinal cord stimulation (SCS) have cylindrical leads that include a lead body with a circular cross-sectional shape and one or more conductive rings spaced apart from each other at the distal end of the lead body. The conductive rings are individual electrodes. In many cases, the SCS leads are implanted percutaneously through a large needle inserted into the epidural space. One concern of cylindrical SCS leads is that they deliver electrical current completely around the lead body because ring-type electrodes typically cover the full circumference of the lead. This is undesirable because the current flow into the areas of the anatomy away from the spinal cord can cause undesirable collateral stimulation. A significant portion of the power is also wasted with cylindrical SCS leads because the energy directed away from the spinal cord does not affect the nerves, but rather it significantly reduces the current density delivered to the target neural tissue. Another challenge of cylindrical leads is that they may migrate after implantation. As such, many cylindrical leads require additional fixation devices to hold the leads at a desired stimulation site.
Another type of stimulation lead is a paddle lead. Paddle leads typically have a relatively flat body with electrodes arranged on one side of the body. Paddle leads are commonly used for cortical stimulation and SCS applications. Large paddle leads are desirable because they cover more neurological structures, but large paddle leads are not well suited for percutaneous implantation. As a result, large paddle leads are often surgically implanted using highly invasive procedures that are costly and can lead to complications. Smaller paddle leads can be percutaneously implanted, but small paddle leads may not be appropriate for many SCS applications. For example, dorsal root SCS applications or other applications may benefit from conventional large electrode arrays that to date have not been implanted percutaneously.